Such heat shields are utilized, inter alia, in the automobile industry in order to line, for example, the floor portion of a vehicle at least in part. Since, with the nowadays customary use of catalysts, the temperatures of the exhaust gases and of the exhaust pipes are greatly increased, such linings have presently become quite popular. Consequently, the disposal of these thermal shields has gained special significance.
Thermal shields as known heretofore consist essentially of a relatively thick formed sheet-metal part having high thermal reflectivity, preferably of aluminum, to which is applied a heat-absorbing insulating layer equipped with a protective foil. The insulating layer utilized herein consists usually of ceramic wool, rock wool, or glass wool, or, respectively, of such foams. Such a thermal shield has been disclosed, for example, in DE-U-87009919.6.
In order to render these thermal shields also acoustically active, it has likewise been proposed to partially perforate the substrate in order to obtain acoustic coupling of the sound waves onto the insulating material of the thermal insulating layer. Such an acoustically effective thermal shield has been described, for example, in Swiss Patent Application 188/90-7. The heat shield disclosed in this application has thermal insulating layers of mineral or ceramic materials, of natural or inorganic materials, or mixtures thereof, optionally also with suitable additives. In particular, mineral foams or ceramic fibrous mats or glass fiber mats, respectively, are used at present for such thermal shields.
These thermal shields, however, can be disposed of for reuse, e.g. recycling only with great effort since the materials utilized for their construction are chosen differently, depending on the manufacturer, and therefore must be individually separated and subjected to a troublesome sorting process in correspondence with the various materials before the materials can be reused, e.g. recycled.